What are the commonly used specs for cylinder chamfering? It seems the "normal" angle is 45º, how deep can you cut to aid reloading? Does the extractor star gets cut the same amount (even chamfering all around)?

I don't see this modification mentioned very often, how useful is it for speed reloads? Does it have any downsides?

There are no "specs" since everyone does it their own way.
Some "specs" if you will:

The ejector IS NOT chamfered.
This really isn't possible without possibly damaging the ratchet area. Chamfering the ejector has no effect on faster reloads, since the only area that really needs to be beveled is the outer arc of the chamber mouth.
Take the ejector OUT before chamfering.

Chamfer only enough to break the sharp edge.
Going deeper really does little good, and may ruin the cylinder and allow swelled or even burst cartridges if enough support is cut away.

Advantages are a slightly faster reload with speed loaders.
Disadvantages are extraction problems or burst cases if too much is done.

Note that too many go too deep the first couple of times they do it. More is not better.
Again, all that's needed is to just break the sharp chamber mouths.

Defariswheel: I had my first one done by a gunsmith who did not bevel the extractor. Worked good. I had to have that cylinder replaced, and the factory beveled the extractor as well and significantly cut the edges. Every gun I have from the factory with beveled chambers has beveled the extractor as well as the cylinder chamber openings. That includes two PC 627's.

I vote for your method. I think less is better when opening the chamber mouths. Just breaking the edge would be enough.

Seems to me you can cut pretty far before your to far past the "web" of the cartridge, and still be safe. I would also think wadcutters would be more suited to a larger chamfer, where ball or JHP, would work fine with minimal chamfer.

Really all that is needed is to break the sharp edge of the chamber. I have used wadcutters in speedloaders a lot of years in PPC in a stock 27 and had no trouble. However, if you want maximum speed like Jerry M can do by just throwing them toward the chamber, a little more might be called for. I just would prefer positive extraction to speed of loading. It is pretty easy to get an empty under the extractor, and this takes a little time to clear.

The brass rim protrudes about .0028"+ in 357 mag/38 spl, so it seems that if the extractor is not touched (or truly "just so", about .002"-.004") and only the outer arc is given a bit more depth it would be OK.

If you had to give a number, how much would be ideal for the outer arc? .004", .008" or .012"

Brass support is not an issue with these numbers, because the brass itself has an unsupported ring of reduced diameter (I guess for some manufacturing reason or to avoid stress concentration) that extends about .025" above the ring.

With all due respect to dfw (who has forgotten more about revolvers than I know), it is possible to chamfer more extensively (at 45°) if you are using auto pistol cartridges (.45ACP, 9x19, .40S&W). They are designed to work with less chamber support than revolver cartridges. This is especially true with a low pressure cartridge like the .45 ACP. I have seen chamfers so big the chambers looked like little funnels, some 0.030" or more. And it's very fast.

If you use the correct sized 45 chamfer tool, you can chamfer the complete chamber, extractor side and all. I normally go up to .03 deep, as you want to break the edge and make it look nice. It does indeed help in speed reloads.
If you have a good steady hand, use a dremel with a 45 grinding wheel, just be careful not to hit the ratchets.

Hello to all,
I looked a bit more closely at my S&W model 65-5 and it seems the chamber is ever so slightly beveled or chamfered. I have no idea how much but it's not a lot. (maybe .020 as "500 Magnum Nut" says) The other end of the chamber, the barrel end, is not at all chamfered. The extractor seems to have the same small amount removed. It's hard to believe this small amount would help but I'm a believer in the littlest things can make a difference. Also noticed a cartridge will not fit in reverse that is to say from the barrel end of chamber. I can see inside the chamber where it is milled out for the .357 or 38 length shell ? Makes sense to me.
No real questions here, more just my observations.
DTz

Please allow the dumb one (me) to ask:
What is the best means to chamfer a 686 cylinder? By that, I mean is there a special tool Brownell's sells for it, or does everyone get out the mighty Dremel and eyeball it?
Thanks for allowing me to intrude on the OP's question
Arman4461

Please allow the dumb one (me) to ask:
What is the best means to chamfer a 686 cylinder? By that, I mean is there a special tool Brownell's sells for it, or does everyone get out the mighty Dremel and eyeball it?
Thanks for allowing me to intrude on the OP's question
Arman4461

I had an old time PPC shooter tell me he used a neck chamfer and deburring tool reloaders use to chamfer the cylinders on his revolvers.
I don't know that it works well, but he said it did.

I recently used the Brownell's chamfering tool on several Model 686's, just breaking the edge at about 45 degrees all round, including the extractor. They still extract correctly, and the slight break seems to help in reloading. Personally, I do not chamfer my own revolvers unless I am interested in speed reloads. The ones I use for speed reloading all happen to be done at the factory and I did not need to do it. If I had, I would have done less than they did, and they should know how much can be done.

I recently used the Brownell's chamfering tool on several Model 686's, just breaking the edge at about 45 degrees all round, including the extractor. They still extract correctly, and the slight break seems to help in reloading. Personally, I do not chamfer my own revolvers unless I am interested in speed reloads. The ones I use for speed reloading all happen to be done at the factory and I did not need to do it. If I had, I would have done less than they did, and they should know how much can be done.

This is one improvement I prefer to let the factory handle, although I'm sure many on this forum have the skill. I probably have the skill but lack the nerve.

I use Brownell's piloted cutter. On non-moonclipped guns I chamfer the cylinder and not the extractor, just blending the tips of the extractor between the chambers with a file. You need the extractor pretty much intact to insure good ejection and to allow the rims to headspace. Moon clip guns are different as the extractor pushes against the moon clip not the case rim.

If you use the correct sized 45 chamfer tool, you can chamfer the complete chamber, extractor side and all. I normally go up to .03 deep, as you want to break the edge and make it look nice. It does indeed help in speed reloads.
If you have a good steady hand, use a dremel with a 45 grinding wheel, just be careful not to hit the ratchets.

500 MN, Do you leave the extractor in the cylinder and cut down with a tool like that sold by Midway? I'm too afraid of cutting the rachet to do that - I haven't found a good way to chamfer the extractor yet.